* {
    margin: 0;
    padding: 0;
}

li {
    list-style-type: none;
}

a {
    text-decoration: none;
    color: black;
}

h1, h2, h3, h4, h5, h6 {
    font-weight: normal;
}

img {
    display: block;
    border: none;
}

body {
    font-family: "微软雅黑";
    font-size: 12px;
}
/* 外部 */
#external {
    width:100%;
    box-sizing: border-box;
    border:1px solid transparent;
}